The present invention relates to a hydraulic system for a torque converter with a lock-up clutch, and more particularly to a hydraulic system for preventing an increase in temperature of hydraulic fluid in the torque converter.
Japanese Patent Application First Publication No. 2-125172 discloses a hydraulic system for a torque converter with a lock-up clutch. The lock-up clutch is disposed in a converter chamber of the torque converter and movable to a lock-up position where it divides the converter chamber into a converter pressure section and a back-up pressure section. In the lock-up position, there is interrupted fluid flow between the converter pressure section and the back-up pressure section. Thus, the hydraulic fluid in the converter pressure section is subject to a temperature increase, inducing deterioration of a clutch facing of the lock-up clutch. This results in a reduced durability of the clutch facing.
An object of the present invention is to improve a hydraulic system for a torque converter with a lock-up clutch such that an excessive temperature increase in hydraulic fluid in a converter chamber is prevented with a simple arrangement.